From 60f7ec90ef817b57b2a35c097456000443d68f1c Mon Sep 17 00:00:00 2001
From: Charlie Marsh <charlie.r.marsh@gmail.com>
Date: Mon, 5 Jan 2026 14:35:43 -0500
Subject: [PATCH] Add a `fast-test` profile (#22382)

## Summary

We use this profile in uv to create success, as an optimization for the
iterative test loop. We include `opt-level=1` because it ends up being
"worth it" for testing (empirically), even though it means the build is
actually a big slower than `dev` (if you remove `opt-level=1`, clean
compile is about 22% faster than `dev`).

Here are some benchmarks I generated with Claude -- the main motivator
here is the incremental testing for `ty_python_semantic` which is 2.4x
faster:

### `ty_python_semantic`

Full test suite (471 tests):
| Scenario    | dev   | fast-test | Improvement |
|-------------|-------|------------|-------------|
| Clean       | 53s   | 49s        | 8% faster   |
| Incremental | 17.8s | 6.8s       | 2.4x faster |

Single test:
| Scenario    | dev   | fast-test | Improvement |
|-------------|-------|------------|-------------|
| Clean       | 42.5s | 55.3s      | 30% slower  |
| Incremental | 6.5s  | 6.1s       | ~same       |

### `ruff_linter`

Full test suite (2622 tests):
| Scenario    | dev   | fast-test | Improvement |
|-------------|-------|------------|-------------|
| Clean       | 31s   | 41s        | 32% slower  |
| Incremental | 11.9s | 10.5s      | 12% faster  |

Single test:
| Scenario    | dev  | fast-test | Improvement |
|-------------|------|------------|-------------|
| Clean       | 26s  | 36.5s      | 40% slower  |
| Incremental | 4.5s | 5.5s       | 22% slower  |
---
 CLAUDE.md  | 6 ++++++
 Cargo.toml | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/CLAUDE.md b/CLAUDE.md
index 289f3bb944..9ed589bf29 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -10,6 +10,12 @@ Run all tests (using `nextest` for faster execution):
 cargo nextest run
 ```
 
+For faster test execution, use the `fast-test` profile which enables optimizations while retaining debug info:
+
+```sh
+cargo nextest run --cargo-profile fast-test
+```
+
 Run tests for a specific crate:
 
 ```sh
diff --git a/Cargo.toml b/Cargo.toml
index cca70fbdc6..f96b83f98f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -335,6 +335,11 @@ strip = false
 debug = "full"
 lto = false
 
+# Profile for faster iteration: applies minimal optimizations for faster tests.
+[profile.fast-test]
+inherits = "dev"
+opt-level = 1
+
 # The profile that 'cargo dist' will build with.
 [profile.dist]
 inherits = "release"